Tissue feed-dog driving mechanism of sewing machines



Nov. 25, 1952 J. KELLER, JR 2,619,058

TISSUE FEED-DOG DRIVING MECHANISM OF SEWING MACHINES Filed May 29, 1946 Patented Nov. 25, 1 952 UNITED STATES TESSUE FEED-DOG DRIVING MECHANISM OF SEWING MACHINES Josef Keller, Jr.,"Rorschach, Switzerland Application Mayi29, 1946, "Serial No. 673,189 in Switzerland June 13, 1945 The present invention relates to sewing machines and more particularly to the driving mechanism for the tissue feed-dog of such machines.

According to the invention thetissue feed-dog carrieris in operative-connection with two rock-- ing shafts by the intermediaryof parallel guide lever means on the one hand and feed lever means acting transversally thereto on the other hand, respectively, which'lever' meansare adaptedto impart to said carrier a quadrangular motion.

The accompanying drawings illustrate, by way of example, one preferred embodiment of the invention.

Fig. 1 is a side elevation of the driving mecha:

from the there is supported between two pivots 2 and 2,

respectively, a feed advance rock shaft 3 which, in known manner, is operatively connected by the levers d and 5 with a stitch adjusting handle (notshown) and which shaft 3 is adapted to perform a-rocking rotation through an angle which varies in accordance with the selectively adjusted stitch length. The rock shaft 3 has formed thereon two lever arms 6 which carry an axle 1. A broad link 8 rotatably connects the Shaft 1 to a spindle 9 of the stirrup-shaped carrier II which carries the feed-dog I'll on a laterally projecting arm ll. provided with two horizontal orrectilinear guideways 12 which extend in said carrier in opposite directions and which receive two roll pins i3 and M for reciprocal motion. The roll pin [3 is rotatably supported by the free end of a semicircular downwardly curved lever it which is rigidly mounted on a feed-lift rock shaft l1 and which extends below and half way round the driving shaft I5 of the loop taker, which shaft is outlined in Fig. 3. The rollpin M is rotatably supported by one end of a lever 18 fixed on an axle l9 which, as seen in Fig. 6, for the purpose of an exact adjustment of the feed-do carrier is eccentrically and rotatably mounted in a sleeve 2| having an eccentric bore 2i. Sleeve 2| is affixed by means of a set screw 2.3 to a frontal plate i of the machine frame I. The curved lever 16 'has'formed therein a longitudinal slit [6, while the curved lever I8 is provided with a crank-like lateral pin or axle [8 Which passes through this slit I6. The shaft ll The carrier H is receives its rocking rotation by the levers 2t], 20' from a lifting eccentric (not shown) and this rocking rotation of the feed-lift rock shaft ll causes the lever 16 to swing up and down. Upon oscillation of the lever Hi, the same causes the lever I8 to swing up and down in an oscillation of equal size'or angular extent as that of lever IS. The feed-lift rock levers l5 and [8 constitute together a parallel motion device which is adapted to impart to the feed-dog carrier H, H and therewith to the tissue feed-dog 10 a vertical up and down motion. Besides this up and down motion the carrier II, II together with the feed-dog I U will be subjected to a horizontal motion, namely, a reciprocating movement transversally to the lever axes ll and'l's, by means of the feed advance rock levers 6 and the link 8.

The combined driving action of the two lever means B, 8 and I5, $8 the latter being of substantially equal length upon the feed-dog l0 causes the same to perform a complete horizontal and'parallel quadrangular motion, the horizontal length of which corresponds to the adjusted stitch length and may be varied between zero and the predetermined limit by means of the stitch adjusting handle.

The feed-dog-driving mechanism according to this invention is of simple and particularly strong construction which needs only little space and is, therefore, specially suitable for sewing machines having a free borne working'support into which this mechanism may be readily built.

During the feeding motion of the tissue feeddog the latter exerts upon the tissue to be fashioned a'constant pressure so that the tissue will be steadily stressed on the whole feeding way.

Summarizing the aforesaid disclosure, it can thus be seen that the feed-dog l9 (Figs. 3, 4 and 5) is attached to a feed-bar or carrier H which is arched to provide two depending legs, the lower end portions of which are formed with horizontally disposed guideways I2. Projecting into one of the guideways 12 is the roll pin 13 carried on the rock-lever It and projecting-into the other guideway is the roll pin it carried on the rock-lever iii. The rock-lever I6 is secured to one endof a feed-lift rock-shaft IT for actuation thereby. The rock-lever i8 is pivoted at its rear end on an axle or pivot-stud 19 -(Fig. 6) freely journaled in the bed of the machine, the rock-lever l8 being adapted to be oscillated or rocked about the pivot-stud i9 through its interconnection with the driven rock-lever l6.

Oscillation of the feed-lift rock-shaft l1 will impart rocking movements to the rock-lever 16 so as to cause the roll pin I3 to rise and fall in an are about the axis of the rock-shaft H. The rocking movements of the rock-lever It will eifect a rocking of the rock-lever [8 about the axle I19, causing roller M to rise and fall simultaneously with roller 13. Since each of the rollers l3 and i4 enter the spaced guidew-ays I 2 provided in the lower portions of the legs of the arched feed-dog carrier I l, the latter is caused to rise and fall vertically without any tipping of the feed-dog l0. Advance and return motions of the feed-dog ll} are derived from the feed-advance rock-shaft 3 through the rocker or link 6 and link 8.

Having thus described the invention, what is claimed as new and desired to be secured by Letters Patent, is:

1. A driving mechanism for the feed-dog of a sewing and like machine comprising a stirrupshaped carrier connected to said feed-dog and having two downwardly depending legs, a transverse guideway provided in each leg, two levers pivotally connected to each other and shaped for attachment to said carrier, respective pivot means at one end of each lever and engaging said guideways, said levers being of substantially the same length from said pivot means to their location of pivotal connection, whereby said levers are adapted to impart reciprocal up and down motion to said feed-dog, means linked to said carrier for imparting to said feed-dog a reciprocal motion transversely to said first-named motion, .and a rocking shaft j-ournalled on said machine, the other end of one of said levers being under the influence of said rocking shaft, the other end of the other lever being pivoted on said machine.

2. A driving mechanism for the feed-dog of a sewing and like machine comprising a stirrupshaped carrier connected to said feed-dog and having downwardly depending legs, a guideway in each leg and extending in lateral direction thereto, two levers pivotally connected to each other and shaped for attachment to said carrier, one end of each of said levers being pivoted in a respective guideway of said carrier, said levers being of substantially the same length from their location of pivotal connection to the pivoted ends, and respective driving means operatively connected to another end of one of said levers and to said carrier above said legs whereby reciprocal up and down motion, as well as a reciprocal motion in transverse direction to said first-named motion may be imparted to said feed-dog, the other end of the other lever being journalled on said machine.

3. A driving mechanism for the feed-dog of a sewing and like machine comprising a centrally located driving shaft, a stirrup-shaped carrier connected to said feed-dog and straddling above said driving shaft, substantially aligned lateral guideways extending in opposite directions and arranged in said carrier at either side of said driving shaft, two downwardly curved levers linked to each other at their median portions thereof and disposed below said shaft and said carrier, means slidably connecting said levers with said carrier in said guideways, and respective means operatively connected with one of said levers and with said carrier for imparting to said feed-dog reciprocal up and down motion as well as a reciprocal motion transversely to said first-named motion.

4. A driving mechanism for the feed-dog of a sewing machine comprising a carrier connected to said feed-dog, said carrier being provided with two laterally extending opposite guideways, two curved levers of substantially equal length linked to each other and extending substantially below said carrier, one end of each of said levers engaging a respective guideway for transmitting a reciprocal first movement to said feed-dog, a

rocking shaft, another end of one of said levers being operatively connected to said rocking shaft, whereby equal oscillatory movement of said shaft will be transmitted to said carrier by said one lever and said other lever linked to the former lever, and means linked to said carrier and imparting to the latter a second reciprocating movement transversely to said first movement.

5. A driving mechanism for transmitting to the feed-dog of a sewing and like machine a fourway motion comprising a parallel motion device including two levers linked at their median portions to each other, a carrier connected to said feed-dog and including rectilinear guideways, one end of each of said levers pivotally engaging a respective guideway of said carrier and positioned on substantially equal level, whereby oscillatory movement imparted to one of said levers causes simultaneous motions of the same extent to both said levers and relatively to said carrier, and oscillatory means linked to said carrier and adapted to impart to the latter a reciprocal motion transversely to the motion caused by said levers.

6. A driving mechanism for transmitting to the feed-dog of a sewing and like machine a fourway motion comprising a parallel motion device including two levers linked at their median portions to each other and crossing thereat, a carrier connected to said feed-dog, one end of one of said levers being arranged opposite and at substantially the same level as the one end of the other of said levers, the respective one ends of said levers pivotally engaging said carrier, whereby oscillatory movement imparted to another end of one of said levers causes up and down motions to both said levers and relatively to said carrier, and oscillatory means linked to said carrier and adapted to impart to the latter a reciprocal motion transversely to the motion caused by said levers.

7. A Work feeding mechanism for a sewing machine having a frame and a loop-taker drive shaft comprising a feed-dog, a carrier for said feed-dog arched to provide a pair of legs straddling said loop-taker drive shaft, feed-lift mechanism including a feed-lift rock shaft operatively connected to one of said feed-dog carrier legs adjacent the lower end of said one leg, feed advance mechanism including a feed advance rock shaft, feed advance rock lever meansconnected to said latter shaft, link means operatively connecting said feed advance rock lever means to said feed-dog carrier, and means supported by the frame and connected to the other leg of the carrier for guiding said other leg during movements of the carrier and for maintaining the feed dog substantially level during operation of the machine.

JOSEF KELLER, 'JR.

REFERENCES CITED The following references are of record'in the file of this patent UNITED STATES PATENTS 

